Approximately 1,000 tornadoes. Nearly 500 dead. The numbers are staggering as the 2011 tornado season rages at a record pace. From the the EF5 tornado that struck Joplin, Mo., killing at least 122 people to become the deadliest tornado in the U.S. since 1950, to the pair of explosive and deadly April tornado outbreaks, and now also yesterday’s Plains outbreak moving east today, this year’s barrage of violent twisters has people asking questions about everything from the impact of climate change on tornadoes, to the accuracy and effectiveness of warnings.
First, on the “are all these tornadoes a manifestation of global warming?” question, there is a consensus on that, but it’s neither comforting nor conclusive. We simply don’t know.
Jeff Masters at Weather Underground: “… this year’s incredibly violent tornado season is not part of a trend. It is either a fluke, the start of a new trend, or an early warning symptom that the climate is growing unstable and is transitioning to a new, higher energy state with the potential to create unprecedented weather and climate events. All are reasonable explanations, but we don’t have a long enough history of good tornado data to judge which is most likely to be correct.”
… one factor that has clearly played a major role in this year’s high tornado death toll: Bad luck. Sure, the more tornadoes there are the better chance that one or more will eventually tear through a highly populated area.
Next, this tornado season has obliterated the notion that massive investment in a national severe weather forecasting infrastructure and early-warning network ensures a low tornado death toll. .
Among tornado researchers, it’s widely recognized that population growth and the increasing urban sprawl is a driving factor that is placing more people in harm’s way. I gave a presentation to the American Meteorological Society several years ago on the challenge of dealing with urban tornadoes, and this issue has only grown in urgency since.
Also relevant is the growth of the portion of Americans who live in mobile homes, which are particularly susceptible to strong winds, be they from tornadoes, hurricanes, or typical severe thunderstorms. … seven percent of Americans – about 20 million people – now live in mobile homes. Also, the greatest share of mobile homes is in the South, where tornado deaths have been especially significant this year.
But making sure that people get the warnings is only half the battle. You also have to get people to take appropriate action once they get the warning, and considering that tornado warnings have a high false alarm rate (as high as 75 percent, by some estimates), people can be forgiven for being skeptical that a given warning will turn out to be the real deal.
Already some are discussing “tornado fatigue” and the ability of the human psyche to distance itself from existential threats, thereby leading people to avoid heeding tornado warnings that could be false alarms (a similar dynamic comes into play concerning climate change, but that involves a longer-term threat).
As Jeffrey Kluger wrote for Time.com, “…paradoxically, what may be the true undoing of good tornado preparedness is the sheer number of the storms themselves. When twisters are touching down by the dozens per day (a whopping 68 were reported in the Midwest this past weekend), being more rather than less prepared would seem the way to go. But familiarity breeds habituation, and habituation, in turn, breeds insouciance.